"We wear white to unite against any attempts by the Trump administration to roll back the incredible progress women have made in the last century, and we will continue to support the advancement of all women," Florida Democratic Rep. Lois Frankel, the chair of the working group, said in a statement to CNN.

House Minority Leader Nancy Pelosi tweeted that the "Democratic #WomenWearWhite in support of women's rights -- in spite of a @POTUS who doesn't!"

Members wearing white say they want to show support for Planned Parenthood, equal pay, and affordable health care, among other causes.

White has become the go-to color for celebrating women in politics at many points throughout history. There was a #WearWhiteToVote movement on Election Day 2016 as a tribute to the suffragettes, who fought for women's right to vote. And on the night Hillary Clinton accepted the Democratic presidential nomination at the Democratic National Convention, she wore a white suit.